Flexible pipes having corrugated metal pipes coated with resins such as soft vinyl chloride, etc. are used for piping for town gas, etc., and from the aspect of easy operation, one-touch-connectible pipe joints are widely used for the connection of flexible pipes. For pipe joints of this type, sealing between flexible pipes and pipe joints should be kept stably for a long period of time, and the normal connection of flexible pipes to pipe joints should be able to be confirmed. Further, an operation manager should be able to confirm the connection of flexible pipes.
JP 2003-56776 A discloses a flexible pipe joint comprising a means (disk spring) performing a click action in cooperation with a corrugated pipe, when a corrugated flexible pipe is inserted to a predetermined position. However, because the click action is sensed by a worker only temporarily, an operation manager cannot determine from the appearance of the pipe joint after connection whether or not a normal operation has been conducted.
Japanese Patent 3538090 discloses a pipe joint comprising a joint body having a cylindrical guide and a hole, a transparent or translucent protection cover attached to the hole, a nut threaded to the joint body, and a ring, a pipe made of a resin such as polyethylene, etc. being attached to the cylindrical guide with the ring disposed between the nut and the guide, the nut being rotated to cause the ring to push the outer surface of the pipe, so that a tip end portion of the pipe attached to the guide can be observed through the hole by the naked eye. In this pipe joint, however, a worker or an operation manager cannot confirm in a narrow, dark connecting site whether or not a normal connection has been conducted.
JP 2004-28112 A discloses a pipe joint comprising in a joint body, a seal packing closely adhered to a flexible pipe, a locking ring slidably attached to and detached from one end of the seal packing, and a slidable ring having an identification pin and engageable with the locking ring; when a tapered surface of the locking ring abuts a tapered surface of the joint body, the diameter of the locking ring is reduced, so that the identification pin in the sliding ring released from the locking ring projects from the joint body. Because the joint body should have a longitudinal hole for introducing the identification pin for confirming the connection of a flexible pipe, this pipe joint is expensive. Also, because the packing is pressed by the flexible pipe to expand longitudinally, its sealing pressure is likely to decrease.
JP 2009-8219 A discloses a pipe joint comprising in a joint body, a movable piece, a sealing member, a packing having a thick portion and a thin portion, and a compression ring for pressing the thin portion of the packing to reduce its diameter. When a flexible pipe is inserted into the joint body to a predetermined position, the movable piece is detached, so that a sound or a reaction can be sensed. Though this pipe joint can keep good sealing, an operation manager cannot confirm from the appearance of the pipe joint after connection whether or not a normal operation has been conducted.